A function is a named block of code which is used to define reusable code that should be easy to use. It is usually included inside a script to help reuse code (to avoid duplicate code) or distributed as part of a module to make it useful for others in multiple scripts.

Scenarios where a function might be useful:

• Calculate the average of a group of numbers
• Generate a report for running processes
• Write a function that tests is a computer is “healthy” by pinging the computer and accessing the c$-share

Functions are created using the function keyword, followed by a single-word name and a script block containing the code to executed when the function name is called.

function NameOfFunction {
    Your code
}

Demo

function HelloWorld {
    Write-Host "Greetings from PowerShell!"
}

Usage:

> HelloWorld
Greetings from PowerShell!